HKS Turbo's vs Garrett Turbo's...

[RS500]

were the standard rods used to allow 9000rpm?

what spec T04's were they (wheel trims, housings, etc)?

btw, which team did u work with back then? were u involved in the ATCC?

thanks dude. your help is much appreciated.

[RS500]

Sydneykid,

sorry for all the questions although i'd like to find out more on what you guys did back in the late 80's, early 90's to extract as much power as you did from the sierra's.

how did u guys go for cams, anything ballistic or not needed when running that much boost?

i am looking at doing cams as to improve the mid-range to top-end power/torque, is it worthwile only to get my exhaust cam re-ground or should i get both exhaust & inlet done at the same time?

[warrick]

sydneykid did you have alook at my question too?any suggestions greatly appreciated.

cheers

warrick

[Steve]

Originally posted by Sydneykid

.......

2. The turbine and compressor covers are machined from Garrett castings, so the are no major differences here ie; I can machine a Garrett cover to fit HKS wheels easily.   In fact a large number of them are unmodified Garrett covers.  As well as performance, this also contrubutes to equal durability.

Leaving the only potential differences being the turbines and compressors.  So you tell me how these two parts that represent less than 25% of the cost of a turbo can make the whole turbo cost twice as much?  A little bit maybe in R&D. but by far the majority of the money goes into promoting the HKS name.

As for me, unless there is good reason, I am not paying extra simply so that HKS can further promote their name.

I think you will find that HKS compressor covers and turbine covers, whilst being manufactured by garrett, are acutally to HKS designed castings. A very clear example of this is the 'S' spec turbos (eg 3037S) - have a close look at the inducer. Also a genuine HKS housing will have HKS on it - so no chance of confusion.

Unfortunately, I have never had the opportunity to compare HKS and garrett housings side by side, but by virtue of the fact that a HKS turbo will keep making good power at 1.5-1.7+bar, which is not likely to happen in a garrett turbo, perhaps there is alot more to it than just a compressor wheel?

[rb20-calais]

Originally posted by RS500

Sydneykid,

point taken although i have a comparison which i usually go by b/w my engine ; a YBD 16v twin cam 2L sierra cosworth engine with the 60-1/T03 sierra wheel (A/R .84 split-pulse exhaust housing) turbo and my friend's 24v twin cam RB20DET with a 400hp Garrett GT25 (-0032 core) with a A/R .64 exhaust housing.

now the drivability of both cars is almost the same (apart from my friend's car having the lower 4.11:1 diff ratio over the 3.64:1 my car has and different g/box ratios) where full boost comes in at about 4200rpm on both engines, but he has slightly more power throughout the rev range.

anyway, my engine managed to make almost the same power as him (me - 221rwkw : 16-17psi vs friend - 227rwkw : 20-21psi) on less boost on the same dyno.

Sydneykid you said I will need around 21psi to get 230rwkw out of a GT25 with 0.86AR, rs500's mate "supposively" got 227rwkw on similar boost with the 0.64AR, I was under the impression that with the 0.86AR i would get a decent amount more rwkw on the same boost?

If I have the choice of any exaust AR because i am getting an rb20 housing machined to suit what do you guys think will be a good exaust AR to get? is 0.86 too big? if i had a 0.86 when would i achieve 1BAR of boost? if the 0.64AR achieves 20psi by 4200rpm would it be safe to say the 0.86AR will get 15psi by 4500rpm?

Any help appreciated.

Thanx

Evan

[EVOIV]

Well, FYI I used to run an HKS GT3037S with 0.6 compressor housing and 0.73 exhaust housing on a 2L engine. It wasn't until around 3500rpm did the car make any decent boost. I think the 0.86 exhaust housing might be OK, but depends upon what you define as "street driveable". But I wouldn't go any larger than a 0.86...that's my opinion anyway.

Just out of interest, where is Garrett from? Is HKS from Japan? It seems that the two most popular choices for turbos in Japan are HKS and TRUST. What brand of turbos do people in the US use? Anyone?

[Sydneykid]

Hi Warwick, sorry I have no personal experience with a 2835, on the other hand the most common application for GT25R is SR20's and they work a treat on them. From my experience the 2540 would be the closest HKS comparison to a GT25R and they are a good choice for an RB20's.

Be careful, there are a number of GT25R's this is the spec we use;

0.64a/r Turbine Housing

0.70a/r Compressor Housing

Watercooled Centre

48 Trim Compressor Wheel

38 lbs/min Comp Flow Max.

76 Trim Turbine Wheel

Integral Wastegate

It is good for 400 bhp (250 rwkw). There is a 450 bhp spec, but I have found it a bit laggy on 2 litres, not so bad on RB25's though.

0.86a/r Turbine Housing

0.70a/r Compressor Housing

Watercooled Centre

48 Trim Compressor Wheel

48 lbs/min Comp Flow Max.

76 Trim Turbine Wheel

Integral Wastegate

Hope that helps

[rb20-calais]

Sydneykid,

Thanks for clearing that up, I think that I will get the turbine housing machined to 0.70AR as well as the compressor housing being 0.70AR. Its should give me a good combo to achieve 230rwkw i hope without massive lag, with this combo do you think it will hit 18psi by 4500rpm?

In a perfect world I would hope that with these specs I would get 18psi by 4500rpm and 230rwkw on 18psi.

Should i stick to 0.64AR turbine housing for my uses (street)? To get 230rwkw do you think I should use a 0.64 turbine with 21psi or a 0.70AR turbine with 18psi ?

Thanx

Evan

[BOOSTD]

"boost is a measurement of resistance of flow"

That makes so much sence =)

Sydneykid: What fuel was the RB25 using to make 250rwkw @1.3bar??? and what A/F ratio

Great Thread guys, alot of valuale information--> keep it flowin(pun intended)

[warrick]

thanks for that sydneykid but i was looking for your suggestion for an rb25det,not the rb20,sorry for any confusion.

cheers

warrick

[RS500]

Originally posted by Steve

RS500,  to address the points you made:

I dont think you read my above post very carefully.

HKS 2530 (rated by HKS at 320ps) made 230rwkw at 1.2 bar boost - that is 395bhp.  I dont think that a turbo of this size is going to make an additional 75hp on .2bar (3psi) THEREFORE HKS UNDER RATE their turbos, not over rate them.

Note the beauty of a HKS turbo is that it will just keep going, where a garrett will be at about its limit by now - HKS turbos reach their max efficiency at 1.5BAR +  This means that a HKS 2530 at 1.2 bar will be able to make MORE than 395bhp - lets see a bush bearing or even ball bearing garrett garden variety turbo do that.  

Steve,

just in the knick of time when i needed it, i have something for you.

FYI, an R32 GTS-T (RB20DET) with a genuine HKS GT2535 was just tuned to 1.4bar (20psi) on the same dyno as mine was (so, no excuses about different dyno readings, etc) and it only made 191rwkw. I must admit, i was told that the power curve is nice and fat so it should feel good on the street but i still find it strange that you say an RB20DET made 230rwkw with the smaller HKS GT2530 at 1.2 bar.

i think the dyno figures might have been tampered with in your example.

Also, going by your 2nd comment above, i'm sure you know that the efficiency and power is not dependant on whether the turbo has a ball-bearing or plain-bearing centre, whereas it will depend on the compressor wheel/housing combination. It's not that HKS turbo's are efficient at 1.5 + bar boost b/c they are ball-bearing, it's b/c they have a well matched compressor/turbine wheel/housing combination.

fyi, a correctly matched compressor side on a plain-bearing turbo will keep on making power over 1.5 bar and that's for sure so again, don't rule out the mighty plain-bearing turbo

fyi, i'll be pushing my turbo tp 1.4 bar soon, so we'll see whether it makes more power or not.

[RS500]

rb20-calais,

i think you should be fine if u went with the A/R .86 exhaust housing as the exhaust wheel (actually, same as HKS GT2530/35/40) isn't very big so it won't be too laggy.

This should allow you to get your 230rwkw goal at about 18-20psi, although max. power would be at higher rpm as compared to when you'd have the turbo with an A/R .64 housing.

good luck and let us know how you go.

btw, did u buy the core off menios?

[Steve]

Originally posted by RS500

Steve,

just in the knick of time when i needed it, i have something for you.

Always handy:)

FYI, an R32 GTS-T (RB20DET) with a genuine HKS GT2535 was just tuned to 1.4bar (20psi) on the same dyno as mine was (so, no excuses about different dyno readings, etc) and it only made 191rwkw.  I must admit, i was told that the power curve is nice and fat so it should feel good on the street but i still find it strange that you say an RB20DET made 230rwkw with the smaller HKS GT2530 at 1.2 bar.  

i think the dyno figures might have been tampered with in your example.

Sorry I didnt include this in original post (oops) but also had a pipe from AFM to turbo as the stocker was sucking shut at around the 200 mark - might be worth your mate checking. I have been in this car (the owner took me for a bit of a high speed drift demo) it definately makes well over 200rwkw. I have been for a spin in an SR20 powered S13 with 360bhp (engine dynoed) that ran 12s - this RB20 (in cefiro) would have absolutely eaten it, so I dont think the figures were fudged.

Perhaps the setup this guy was using is crap, because that just doesnt make sense that a 2535 would flow less than a stock rb25 turbo can???? It would be really easy to say someone only got xxx rwkw, but unles you know exactly what mods etc, it is no way to guage the actual potential of a turbo.

Also, going by your 2nd comment above, i'm sure you know that the efficiency and power is not dependant on whether the turbo has a ball-bearing or plain-bearing centre, whereas it will depend on the compressor wheel/housing combination.  It's not that HKS turbo's are efficient at 1.5 + bar boost b/c they are ball-bearing, it's b/c they have a well matched compressor/turbine wheel/housing combination.

fyi, a correctly matched compressor side on a plain-bearing turbo will keep on making power over 1.5 bar and that's for sure so again, don't rule out the mighty plain-bearing turbo

Not argument there, I do agree completely. I was actually referring to garrett bb turbos which dont seem to do alot over 1 bar - as they start to move out of their efficiency range. I am not saying this is the absolute case with all garrett bb turbos, I am generallising based on what I have experienced, and the experiences of people contributing here.

fyi, i'll be pushing my turbo tp 1.4 bar soon, so we'll see whether it makes more power or not.

Good luck, I hope it goes well.

I dont think I am as down on plain bearing turbos as perhaps sydneykid. Maybe its because he has been burnt along time ago when plain bearing turbos couldnt hold a candle to bb. I think technology has narrowed the gap greatly, but not overtaken yet.

My comments were purely based on the belief that HKS turbos, when correctly matched to an engine, will walk over any garrett garden variety turbo that you buy. The technology that goes into these turbos is not available from anyone but HKS.

I have seen comments on here from guys that have purchased new turbos from GCG, and it has taken them 3 goes to get it right, turbo keeps surging, not making good power. HKS have far more resources available to develope a turbo, it takes them months and months of dedicated research and design - unfortunately no one here in aust can match that. How many companies here have compressor housings made to their own design?

the japanese have been making these turbos for use on these cars for many many years, probably before most people in australia have been anywhere near a turbo. Wasnt it HKS that originally came up with the whole turbo idea?

Sydneykid, didnt you once comment that the best setup you have driven was with HKS 2530 turbos on a skyline - if my memory serves me correctly:D

[zforce]

Steve,

So you think that on a RB20DET a HKS GT2530 will flow 400hp (250rwkw), or should a bigger turbo be chosen? There will be other mods (cams, head work, no internals) to add in getting the power, but correct me if i am wrong, i understand that an engine can only make the power (give or take a bit) that the amount of air a turbo can flow. E.g. if a turbo can flow 300hp of air, then the engine can only make 300hp (+- 10hp or whatever the tolerance is).

[RS500]

Steve,

it's all good dude.

my comments were based on my belief that the garrett gt turbo's are just as good as the hks, except for the lack of options in different comp. housing A/R's. This is where i believe most of the difference in response and compressor efficiency is seen b/w the garrett and hks turbos.

actually, my same friend with the R32 GTS-T (as mentioned above) which made 227rwkw with a 400hp garrett GT25 (-0032 core) on 20-21psi, has actually purchased a genuine HKS gt2540 and he'll be doing back to back testing on the same dyno so it'll be interesting to see the results.

I'll keep you all posted.

[Steve]

zforce,

I really dont know for sure, but I would love to see what happens when the boost is wound up to 1.5-2bar on the 2530.

Working on 250rwkw, 'theoretically' it would be possible if you are making 230rwkw at 1.2 bar. Working on 10hp per pound of boost, it would require an extra 3lbs of boost to make 250rwkw. (maybe 4 lbs for addition drivetrain loss).

The HKS 2530 is rated at 320ps by HKS. HKS rate their turbos at 1 bar and allow 10% error, ie rate them 10% low.

This works true for my example above. If we allow 50kw loss for drive train, the engine must be making 280kw for 230rwkw @ 1.2 bar.

Reducing boost by .2 bar (3lbs) = 30hp, or 22kw, would mean the engine is making 260kw or 354hp (pretty close to 320 +10% or 32hp) that it is rated at.

So, as mentioned in 'theory' the turbo could flow that sort of power without too much problem at higher boost.

The above calculations were based on 0.735hp/kw.

I think it would take a very well set up car to be able to do it, as losses tend to be higher the higher the boost, not only do you get increase in driveline loss (minimal?) but you also start moving alot of components out of their comfort range (TB, plenum, ECU, AFM, manifold etc) I would really love to see if it is possible in the real world, not just on paper:D

RS500, that would be a great comparison. I would be interesting too because the HKS2540 is touted by many to be one of HKS's worst turbos, and indeed on GTRs (in twin form) they appear to not do much until you wind in a heap of boost, unlike the 2530s which seem like they were made for the job. There doesnt seem to be too many people running them in single form. Very interesting.

Try and get as much info on housing sizes, wheel trims etc if poss. it will be a really good comparison especially if they are similar in spec!

Also, if there is anyone in SA running an externally gated GT30 powered SR20 or similar, I have a HKS 3037 with gt25 flange that is just begging to be compared on a dyno - perhaps this is one that HPI or ZOOM should get their teeth into, do a direct comparison between HKS turbos and closely matched garretts - would dispell any myths very quickly -

benHPI??????

[Guest INASNT]

obly proble i can see with the small turbos like thr 2530 are that they come on 2 early and cause 2 much wheel spin then run out up top

[rb20-calais]

RS500,

Yes I bought the turbo off Menios and I must say he is an awesome bloke!

I think I will try to go with an AR of maybe 0.75 or so just to get some kind of balance between power and response.

When you say that because the exaust wheel is the same size and response wont have much difference between the 0.64 and 0.86 do you know roughly a ball park figure of when 1BAR would hit with an RB20?

I would go with a 0.86 but i am scared i wont see 1BAR till after 5000rpm. Will the difference in lag be massive?

Thanx

Evan

[RS500]

Originally posted by rb20-calais

RS500,

Yes I bought the turbo off Menios and I must say he is an awesome bloke!

I think I will try to go with an AR of maybe 0.75 or so just to get some kind of balance between power and response.

When you say that because the exaust wheel is the same size and response wont have much difference between the 0.64 and 0.86 do you know roughly a ball park figure of when 1BAR would hit with an RB20?  

I would go with a 0.86 but i am scared i wont see 1BAR till after 5000rpm. Will the difference in lag be massive?

Thanx

Evan

rb20-calais,

damn, i was trying to get in contact with him about the turbo.

i'm not too sure how it will be with the .86, although what i was trying to say is that seeing as though the exhaust wheel is not very big it doesn't take much exhaust gas to get it spinning hard so it shouldn't be too laggy.

Although, my friend has the -0032 GT25 turbo on his RB20 with a A/R .64 and boost comes in hard at about 4200rpm (with heaps of boost creep before 10psi) so it can be bettered.

One thing to know though is that his turbo has a 56 trim GT35 wheel in an A/R .60 compressor housing which helps it hold efficiency at higher boost whereas you have a 48 trim T04S wheel in an A/R .70 comp housing which will introduce more lag than my friend's turbo, so yeah, maybe you're better off going for the .64 exhaust housing.

[rb20-calais]

RS500,

I think that I will go with the 0.64AR exaust housing after these comments. I could always get it machined more at a later date if I wanted.

When you say a lot of boost creep before 10psi what exactly do you mean?

Also when I get my wastegate actuator should i get one with a 15psi spring in it and then bleed to 18-20psi? I have a wolf 3d and i am pretty sure it has an inbuilt EBC, anyone know much about this?

Thanx

Evan